In the communications industry, millions of electrical connections between insulated conductors are made each year. These connections must be easily and inexpensively made. Also, the electrical connections which are made must be reliable and must be maintained over a period of time during which forces may be applied to the insulated conductors.
Some connections, which are called in-line, are made in the factory during processing of the insulated conductors and cable which includes the conductors. A trailing end of one supply of an insulated conductor must be spliced to a leading end of another supply to allow continuous processing. Typically, these splices have been made by the use of a solder ring in a heat shrinkable plastic tube or by brazing, both of which rely on the application of heat energy and on operator dexterity. Connectors which are used in factory splicing must be capable of being advanced over sheaves, for example, during further processing. Other connections are made outside the factory, in the field, under conditions which require simplicity and low cost.
Connectors are available which do not require the stripping of the insulation from an end of the conductor prior to making the connection. Such connectors are widely used and are known as solderless connectors. One such solderless electrical connector for insulated electrical conductors is referred to as a B-wire connector. It includes a plurality of coaxially telescopically disposed sleeves including an inner sleeve of electrically conductive material and an outer jacket of electrically insulating material. The inner sleeve is provided on its inner surface with spaced apart perforations defining inwardly extending insulation-piercing and wire-engaging tangs. A pair of insulated electrical conductors or wires may be inserted into the inner sleeve. Their end portions are confined and embraced by the tangs on the inner sleeve. Electrical contact with the metallic portion of the wires is established when the connection is deformed by pressure applied on the outside thereof. A crushing action is thereby exerted on the inner sleeve, forcing the tangs through the insulation and causing them to engage the metallic conducting portions. One such connector is more fully described and illustrated in U.S. Pat. No. 3,064,072 granted Nov. 13, 1962 to H. T. Graff et al.
Connectors of this type have been used by the millions. However, difficulty has been experienced in that upon insertion into the inner sleeve, the conductors may hang-up on the inwardly projecting tangs. Although an operator may play the conductors free of the tangs during assembly thereof, which in itself may be time-consuming, there is no assurance that the conductors have bottomed within the connector. This connector is relatively inexpensive and easy to use without the necessity for special hand tools, but it relies on a crimping operation to establish the electrical connection. As a result, contact resistance may change significantly with age.
Another type of solderless splicing connector which is most economical for a relatively small number of connections is one which is shown in U.S. Pat. No. 3,012,219. It uses a U-shaped contact element being made of a metallic material and having upstanding bifurcated end portions that are received in a plastic housing. A slot formed at each end extends inwardly and is adapted to receive an insulated conductor. A plastic cover is mounted in a first position on the housing. Conductors are inserted into openings to cause the conductors to be aligned with conductor-receiving slots formed in the upstanding bifurcated end portions. The cover is moved to a second position on the housing to cause the conductors to be moved into the conductor-receiving slots. Because the slots are narrower than the diameter of the wire portions, the insulation is penetrated and contact is made between the exposed conductors and the contact elements.
A split beam contact element which is widely used in telecommunications for interconnecting insulated conductors includes a center portion with beams extending colinearly thereform. Each of the beams is bifurcated with the furcations of each forming a conductor-receiving slot. A plurality of the split beam contact elements are mounted in a dielectric housing. To establish a connection, an insulated conductor is moved into one slot and another conductor into the opposite slot. Surfaces that define the entrances to the slots and the slots themselves are configured to engage the conductive element of each conductor to establish an electrical connection between the conductors. This is a stored energy connection device. Should the conductor relax with age, the resilient furcations of the beam move together to re-establish a gas-tight connection. See for example U.S. Pat. No. 3,496,522 which issued on Feb. 17, 1970 in the names of B. C. Ellis et al and U.S. Pat. Nos. 3,611,264 and 3,772,635. Connector systems such as that shown and claimed in U.S. Pat. No. 3,858,158 which issued on Dec. 31, 1974, in the names of R. W. Henn et al are available for splicing together a plurality of conductors simultaneously.
Although the priorly described U-shaped contact element connector and those typified by the Ellis and Henn patents are suitable for field connections, they are not adaptable to connect conductors that are further processed in a factory. The so-called B-wire connector approaches the sought-after connector, but it falls short of the desired reliability, is too time consuming in its use and is too large for subsequent processing. Also, it is not an in-line connector, inasmuch as the conductors to be spliced are disposed side-by-side and inserted into the same end of the connector.
Notwithstanding the availability of these connectors for splicing, there is still a need for one that is adapted to universal use in the factory and in the field. The sought-after connector must be one which may be used to establish an in-line connection between two conductors, said connection being one which does not inhibit further processing. It also should be one which does not require the use of heat and which is not operator-sensitive. The connector also should be one in which the connection is a mechanical one as opposed to one which relies on soldering or brazing. A further consideration should be that the connection is able to be made without the need for tailoring the length of the conductor to the connector. Rather, it should be one where the conductor ends are postioned in the connector after which excess ends are severed.